The present invention is concerned with a device for eliminating the chatter or bounce of a relay armature which is returning from its energized position to its rest position. In general, chatter or bounce during the impact of masses affects the life of mechanical equipment, more particularly, as far as relay armatures are concerned, chatter affects the life of the surfaces at the points of contact. Another special problem also occurs in electrical circuits having a mechanical contact such as a relay contact when the mechanical contact is in the closed position. Chatter at this mechanical contact results in the repititious opening and closing of the electrical circuit. This produces spark formations, welding processes, transfer of material at the contact point and, frequently, undesirable burst noises within the electrical circuit.
The actuation of a relay armature in the direction of energization, which is caused by the magnetic forces of the relay coil, usually does not result in substantial bounce or chatter since in this position the relay armature is continually exposed to considerable magnetic forces. On the other hand, upon returning to its rest position, the relay armature is subject to the force of the armature spring which is designed so weak that its force, which opposes the armature energization, affects the response sensitivity and pickup time of the relay. This exerts great influence on the amplitude of the rebounces on impact of the armature with its stop. Thus, during the release of the armature, the relay contacts may again be actuated by the rebound from the rest side stop, resulting in all of the above disadvantages which deleteriously affect the life and functional capability of the relay.
Past devices have attempted to minimize the problem of the tendency of relay armatures to bounce by placing additional masses on the relay armature which were capable of moving independently thereof. For example, it is possible to attach freely moving masses in casings to the relay armature. The movement of these freely moving masses lags behind the particular movement of the relay armature and produces a counter force when the armature rebounces. Also, by means of bent springs an additional overshooting mass may be placed on the relay armature. However, all these previous solutions suffer the disadvantage that they adversely affect the response of the relay armature to energization due to the additional masses placed on the armature. As a result, higher energies must be generated for the excitation of the relay. Apart from these higher energies, cost disadvantages accrue due to the increased size of these relays due primarily to the change of the cross sectional area of the relay coil.
The arrangement of additional masses on relay armatures also appears virtually impossible in the case of minature relays which have found increasingly wide application. The adjustment and checking of these additional masses to ensure the proper functioning of the relay are accompanied by precise mechanical problems which cannot be economically solved. In particular, these relays operate with very small air gaps due to their small size and, as a rule, their armatures must be designed to ensure extra positive contact making. To this end, these relays often employ springs fitted over the socket contacts to increase spring travel. However, in these relays, even a minimum susceptibility to rebounce during release causes the contact to close again with all the attendant disadvantages described hereinabove.
Accordingly, it is an object of the present invention to develop a suitable solution for damping the releasing movement of relay armatures in order to avoid the bounces or chatter that may cause the relay contact to close again.